Method of making selective switch contacts

ABSTRACT

This invention relates to a switch having four parts including the housing. More particularly the invention relates to a frame which has 16 positions which can be binary coded. The sixteen positions consist of four single pole-double throw contacts all of which are made by stamping and forming a single sheet of metal. The movable contacts are switched from one fixed contact to another by lobes on a rotatable camshaft.

3, 31,272 [4 Aug. 27,1974

United States Patent [191 Purdy 3,621,157 11/1971 ZOO/6B8 3,772,485 11/1973 Workings........................ZOO/166B METHOD OF MAKING SELECTIVE SWITCH CONTACTS [75] Inventor: Harold Lawrence Purdy,

Hummelstown, Pa.

[73] Assignee: AMP Incorporated,

Primary Examiner-Charles W. Lanham Assistant Examiner-James R. Duzan Harrisburg, Pa.

Attorney Agent or FirmAl1an B. Osborne, Esq.

22 Filed: Sept. 18,1973

21 Appl. No.: 398,505

ABSTRACT Related US. Application Data [62] Division of Ser. No. 306,1 13, Nov. 13, 1972, Pat. No.

This invention relates to a switch having four parts including the housing. More particularlythe invention relates to a frame which has 16 positions which can be binary coded. The sixteen positions consist of four single pole-double throw contacts all of which are made by stamping and forming a single sheet of metal. The movable contacts are switched from one fixed contact to another by lobes on a rotatable camshaft.

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[56] References Cited UNITED STATES PATENTS 3,359,392 12/1967 200/6 BA 4 Claims, 7 Drawing Figures METHOD OF MAKING SELECTIVE SWITCH CONTACTS This is a division of application Ser. No. 306,113, filed Nov. 13, 1972 now US. Pat. No. 3,792,206.

BACKGROUND OF THE INVENTION Multi-circuit or selective switches are utilized in many applications. One such application which is becoming extremely important is that of having a means whereby printed circuit boards or an electronic device is capable of accepting or rejecting a message. For example,'where onewishes to communicate with a particular circuit board which is only one among many allelectrically connected boards, an addressing signal mustbe sent preceding the message. A selective switch which is mounted on each board is programmed to open thedoor to its board only when the addressing signal matches a particular code therein. The code will consist of a number of circuits which are opened or closed in a pre-determined combination. An analogy to this electronic switch is the manually operated combination lock.

Selective switches currently available are made from a large number of parts. For example, some contact arms are separately fashioned with a highly conductive contact point being riveted or soldered thereonto. Thus, in a switch having four poles, and with double throw (four movable contacts and eight fixed contacts) there couldbe a minimum of 28 separate pieces in the contact assembly alone. Added to these 28 pieces, there are detent springs, detent plates and so forth. Obviously,thistype of switch is costly to make and further the manufacturing process does not lend itself readily to automation.

Another problem which workers in this field are faced with is the spacing between printed circuit boards in installations such as computers, telephone ex- 1 changes, airplanes and the like. As space is generally at a premiumin such installations, the circuit boards are stacked as close together as possible. The pluggable components such as the selective switches must have as low a profile as possible. The miniaturization of a large number of discreteparts obviously increases manufacturing costs as well as decreases operating life and reli ability.

Accordingly, it is an object of the present invention to provide a complex sixteen position binary codable selective switch having four discrete parts including the housing and which can be mass-produced using high speed automation.

Another object of the present invention is to produce a switch adapted to control electric circuits on a selective basis.

Other objects and features of the invention will become apparent from the following description of the preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 isa view of a completely assembled binary codable selective switch;

FIG. 2 is an exploded view of a preferred embodiment of the switch in FIG. 1 less the cover;

FIG. 3 is the contact frame of FIG. 2 after stamping operations;

FIG. 4 is the contact frame of FIG. 3 after forming operations;

FIGS. 5 and 6 are cross-sectional views taken along lines 5--5 and 6-6 respectively of FIG. 1; and,

FIG. 7 is another preferred embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates acompletely assembled binary codable dual in-line package switch 10 ready for use in'a printed circuit board (not shown) or the like. The components of switch 10 include the upper cover member 12 of housing 13. Depending from the housing are pins or connecting posts 14 which are adapted to be received in female receptacles, sockets, or holes in a printed circuit board (not shown). The end wall 16 of cover member 12 has an opening 18 in which is positioned the slotted end 20 of camshaft 38 (FIG. 2). Encircling opening 18 are position indicators 22.

FIG. 2 is an exploded perspective view of the components within switch 10. The lower half of housing 13 is base member 24 having sidewalls 26 on which are contained on its outer surface, vertical grooves 28. End walls 30 have elongated, U-shaped slots 32 opening upwardly. Intermediate to end walls 30 is a dividing wall 34 which sections the interior of base member 24 into two compartments 35. As with walls 30, .dividing wall 34 also has a U-shaped upwardly opening slot 32.

Immediately above base member 24 is .the aforementioned camshaft 38. The camshaft has three annular bearing surfaces 39, one on either end (only the right sided one can be seen) and a third one in the middle which separates camshaft 38 into two halves. Both halves contain two distinct, side by side cams 44 positioned between two detent surfaces 46. The positioning of the flanks 47 and lobes 48 on cams 44 have been pre-determined to yield specific results as will be discussed below. The detent surfaces 46 contain a plurality of hills 49 and valleys 50. In the assembled switch camshaft 38 is positioned within base member 24 with annular bearing surfaces 39 rotatably positioned in slots 32 and each half of the camshaft in one of the two compartments 35.

Positioned above camshaft 38 are a plurality of contact members 56. The members each have a shank or intermediate portion 58, the aforementioned posts 14 at the outer ends, and on the other end inner por tions 60 which have been bent normal to the intermediate portion 58. As these contact members form an important part of the instant invention, they will be considered in detail below. Suffice it to say that there are four detent springs 62 and four movable contact arms 64 each of which are engageable with two fixed contacts 66-68.

In the assembly of switch 10, the contact members 56 fit down over the camshaft 38 positioned in base. member 24 with the inner portions 60 extending across the openings of compartments 35 with each of the movable contact arms 64 in registration with one of the four cams 44. Each of the four detent srpings 62 are loaded against one of the four detent surfaces 46 so that a firm intentional effort is required to rotate camshaft 38 and so that the camshaft is protected against unintentional movement induced by vibrations. To this end, the detent springs may be designed to response to different resonant frequencies. v

FIGS. 3 and 4 show the development of contact members 56 by stamping and forming operations performed on a strip roll of metal (not shown) having suitable dimensions. Although several different metals can be used, phosphor bronze has been found to work quite satisfactorily.

In FIG. 3 a frame 70 has been stamped from a strip roll of metal (not shown). On either end are connecting straps 72 which lead to and from other like frames (not shown). Running transverse to and integral with straps 72 are two end strips 74, each of which contain a positioning hole 76 located on the frames longitudinal axis. Between the end strips and parallel thereto are the two rows of eight contact members 56 each. The posts 14 extend outwardly and the contact portions 60 project inwardly with respect to the frames longitudinal axis.

Web portions 78 connect contact members 56 with end strips 74. These web portions are located adjacent to posts 14. Although this location for the web portions is preferred because it adds stability to the contact members 56 both during the forming operation and assembly of switch 10, it has been found that the removal of the web portions subsequent to assembly is facilitatecl if such portions were located at or near the free ends of posts 14.

FIG. 4 shows frame 70 ater the forming operation. The midsections of end strips 74, hereinafter designated generally at 80, and inner portions 60 have been bent to form the bight on the U-shaped configuration while the ends of end strips 74, posts 14, intermediate portions 58 and web portions 78 form the legs.

Each contact member 56 is separately identified by a small letter beginning with 0, attached to the reference numeral 56 for the purpose of describing the structure of the inner portions 60.

The contact portion of member 56a is biased or loaded downwardly relative to midsection 80 and further a section designated at 82 and adjacent the free end of the inner portion, has been dimpled to form detent spring 62 (FIG. 2).

The contact portions of contact member 56b, contains a laterally extending tab 84 which has been bent so that its contact area 85 is in a higher horizontal plane than for example the midsection 80 of end strip 74. Tab 82 so formed is the fixed contact 68 (FIG. 2).

The inner portion 60 of contact member 56c (adjacent to 56a) has been swaged as seen at 86. The swaging has extruded the contact portion further toward and overlaps its opposing contact member (56d) and extends beneath lateral tab 84; i.e. fixed contacts 66 and 68. Further, the swaging has increased the flexibility of the inner portion 60 and has hardened the material allowing higher stress levels. The contact portions of 560 have also been dimpled between the free end and the swaged area to create a convex surface 88 which is dimensioned to rest conformably in a flank 47 on cam 44 (see FIG. 5). The inner portion 60 on contact member 560 formed as described above constitutes movable contact arm 64 (FIG. 2).

The inner portion 60 of contact member 5611, positioned adjacent member 56b and oppose member 560, is generally rectangular platform 90 which constitutes the fixed contact 66 (FIG. 2). As the platform on contact member 56d has been obscured in FIG. 2 by movable contact arm 64, reference is made to contact member 56f which clearly show the platform and as will be seen is identical thereto.

Contact members 56a, b, c and d form one set consisting of a detent spring 62, movable contact arm 64 and fixed contacts 66-68. This set has a mirror image in all respects in members 56e, f, g, andh. These two sets form a first group having double pole-double throw characteristics. A second group but orientated degrees therefrom, consists of contact members 561', j, k, l, m, n, 0, and p. The two groups together, along with the particular cam 44 configurations, operate in 8-4-2-1 binary sequence. As is apparent, the cam 44 configuration and contacts can be varied to produce any sequence as desired.

FIG. 5 clearly shows the relationship between the several components in switch 10. Camshaft 38 is seen rotatably positioned in base member 24 of housing 13 with annular bearing surfaces 36 seen in phantom positioned in openings 32. The figure also clearly shows the swaged area 86 on movable contact arm 64 as well as the positioning of its free end in between the two, vertically spaced-apart, fixed contacts 66-68. Contact arm 64, biased against fixed contact 66, is moved into engagement with fixed contact 68 by rotating camshaft 38 to where a lobe 48 elevates the arm.

FIG. 5 also shows the general construction of cover member 12 and its relation to contact members 56 and base member 24. As is well understood in the art, the housing members are bonded together to make an environmentally sealed package.

FIG. 6 illustrates the relation of detent spring 62 to detent surface 46. The view shows the interaction between dimple 82 and the hills 49 and valleys 50 on surface 46. The angles thereon are steep to require some force to rotate camshaft 38 and also to provide a snap action as detent springs 62 cam over a hill into a valley.

FIG. 6 also includes an end view of fixed contact 68 showing the vertical offset thereof.

FIG. 7 illustrates the adaption of the switch disclosed herein to a single pole (one movable contact arm 62) and a single throw (fixed contact 66). It is clear that fixed contact 68 could be used in lieu of contact 66. Camshaft 38 incorporates a single cam 44 having a single lobe 48. Base member 24 has but a single and shorter compartment 35 and of course cover member 12 would also be proportionately smaller.

It is apparent that cam 48 in FIG. 7 could have a single flank 47 instead of a single lobe 48.

With the exception of contact members 56 the other three components of switch 10; i.e., cover and base members 12-24 and camshaft 38, are made of plastic or other insulating material.

In summary the present invention discloses a switch consisting of a limited number of easily available components with the contact members being made from a single strip of material by stamping and forming without adding another single discrete element. However, as is well known in the industry, the contact members may be plated with gold, tin or the like to enhance the metals electrical characteristics but this is a matter of choice rather than need.

The present invention is ideally suited for use as an address to a printed circuit board such that access to the board is gained only by a select signal. It is apparent to one skilled in the art that a board having thereon the switches herein disclosed can be given a new address at any time without removing the switches from the board and with the only required tool being a screwdriver.

It is further apparent that the switch disclosed herein, having a total of four parts, is readily adaptable to manufacturing via automation.

The present invention is not limited to a single pole, single throw or a dual double pole, double throw embodiments. It will be clear to those skilled in the art that any number of combinations can be made.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as some modifications will be obvious to those skilled in the art.

d. shaping one of said inner portions to form a first fixed contact; and e. shaping the inner portion opposite said first fixed contact to form a movable contact arm; and f. shaping the inner ends positioned on a row opposite said second fixed contacts to form detent springs. 2. The method of claim 1 further characterized by the additional step of swaging said movable contact arm to extrude the free end thereof into an overlapping relation with said first fixed contact.

3. A method of making contacts useful in electromagnetic relay assemblies comprising the steps of:

the

stamping planar sheet of conductive material to form a frame comprising two parallel rows of parallel contact members, said contact members being in two groups one group being identical to the other with each group having four contact members in one row and the four contact members in the opposite row in opposing relation, said contact members each having an intermediate portion, a connection post on one end of said intermediate portion and an inner portions on another end of said intermediate portion, said inner portions of said members on one row facing said inner portions of other said members on another row;

bending said frame into a U-shape where said inner portions form the bight thereof; and

. forming said inner portions to provide in each group two sets of contacts comprising two first and two second fixed contacts formed from four adjacent inner portions on the same row where each of said first fixed contacts are spaced above one of said second fixed contacts, and two movable contact arms formed from two adjacent inner por tions on the opposing row, and two detent springs formed from inner portions positioned on the same row as and on either side of said movable contact arms.

The method of claim 3 further characterized by additional step of swaging said movable contact arms to extrude the free ends thereof into the space between said first and second fixed contacts.

22 3 I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3.831.212 Dated August 27 1974 Inventor(s) HAROLD LAWRENCE PURDY It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Colunm 6, line 5, e'fter the word "stamping" insert the word --a-.

si ed and sealed this 29th day of October 1974.

(SEAL) Attest: I I

M COY M. GIBSON JR. C. MARSIjALL DANN Agtesting' Officer Commissxoner of Patents AMP 2884 

1. A method of making selective switch contacts comprising the steps of: a. providing a planar sheet of conductive material; b. stamping said sheet to provide a frame comprising two parallel rows of one contact member each, said contact members each having an intermediate portion, connecting posts at one end thereof and an inner portion at another end, said inner portion of one contact member projecting towards said inner portion of the other contact member; c. forming said stamped frame into a U-shaped form to where said inner portions form the bight thereof; d. shaping one of said inner portions to form a first fixed contact; and e. shaping the inner portion opposite said first fixed contact to form a movable contact arm; and f. shaping the inner ends positioned on a row opposite said second fixed contacts to form detent springs.
 2. The method of claim 1 further characterized by the additional step of swaging said movable contact arm to extrude the free end thereof into an overlapping relation with said first fixed contact.
 3. A method of making contacts useful in electromagnetic relay assemblies comprising the steps of: a. stamping planar sheet of conductive material to form a frame comprising two parallel rows of parallel contact members, said contact members being in two groups one group being identical to the other with each group having four contact members in one row and the four contact members in the opposite row in opposing relation, said contact members each having an intermediate portion, a connection post on one end of said intermediate portion and an inner portions on another end of said intermediate portion, said inner portions of said members on one row facing said inner portions of other said members on another row; b. bending said frame into a U-shape where said inner portions form the bight thereof; and c. forming said inner portions to provide in each group two sets of contacts comprising two first and two second fixed contacts formed from four adjacent inner portions on the same row where each of said first fixed contacts are spaced above one of said second fixed contacts, and two movable contact arms formed from two adjacent inner portions on the opposing row, and two detent springs formed from inner portions positioned on the same row as and on either side of said movable contact arms.
 4. The method of claim 3 further characterized by the additional step of swaging said movable contact arms to extrude the free ends thereof into the space between said first and second fixed contacts. 